Re: WANTED: Information on Apple II copy protection

[Rubywand <rubywand@swbell.net>]

mkelsey@spam.eecs.wsu.edu writes ...
> 
> In article <350F830D.B36A2C41@swbell.net>,
>         Rubywand <rubywand@swbell.net> writes:
> > Michael Kelsey - Systems Staff writes ..
> >>
> 
> >      Shamus, Frogger, and Frogger II have all been cracked. There is no
> > information about Shamus's original protection. My version is a copy-- a
> > file included with a couple other games on a diskette side.
> 
> Right.  Before Asimov was up and running I didn't even know that anybody
> else in the world even had Shamus.  Well, hmmm..I would still like to
> know what protection it uses.  It appears to be VERY sensative to disk
> speed.  I felt like I was cheating by capturing it in memory; other than
> the fact that I was able to finish playing out the game; it didn't have
> any type of save feature :P
> 
> One of two reasons why disk speed might be an issue:  synchronized
> tracks OR it relies on accurate disk speed to "place" it at the next
> correct sector.  Like I stated before, it uses huge gaps of invalid
> bytes and "bing!" suddenly valid data follows.  What other programs
> did Synapse make around 1983?  Maybe this can shed some light. ....
>

     Synapse released a number of games (e.g. Drelbs); but, info on
these is no easier to locate than info on Shamus. (One way to track down
games from a company is to visit James Hague's Giant List' at ...

 http://www.dadgum.com/glist/list.html  and search for the company
name.)


     The protection you describe sounds like some kind of variable track
length scheme which may also employ a 13-sector DOS. Long tracks tend to
be fairly speed sensitive.



 
> >      Sega .... One Computist contributor outlined patches ....
> 
> Do you know where I might begin looking for this outlined patch?  I never
> subscribed to Computist and learned everything by experimenting with
> (many many) bit copiers.  I wouldn't even know what time frame to begin
> looking!
>

     The patch is a few mods to DOS to ignore errors. The copy process
is described by Jeff Root in Computist #72 ...

 1. INIT a blank diskette for ProtoDOS

 2. Boot the DOS 3.3 System Master with FID (or other DOS diskette with
FID).

 3. Get to the standard DOS prompt and go to the monitor (CALL-151).

 4. Make the following changes:

    $B954: 29 00 (ignore 1st address byte)
    $B98A: 00 (ignore address checksum)
 
 5. Exit monitor to BASIC (CTRL-C, RETURN)

 6. Start FID (BRUN FID)

 7. Copy Frogger to INITed diskette (enter "Frogger" for the file name). 

 8. On the INITed diskette save a short HELLO program to start the game
...

    10 PRINT CHR$(4);"BRUN FROGGER"


     The author describes this as a "98% crack" because status line
results are erratic. But, he says that he has been able to play the game
through several screens with no problem.


 
> > to be the one you used-- i.e. capturing the program in RAM.
> 
> With the exception that Frogger "parked" it's hires font at $0300 or $0400;
> I don't remember which, but I know it was impossible (for me) to obtain.
> The Control-ClosedApple-Reset technique would cost you everything from
> $0000-$0802.  I had to rip off the font from the only other program
> I had from that era - CannonBall Blitz.  Other than that, it was
> the only way I could make an efficient operable copy of Shamus, Frogger
> and Where in the World is Carmen Sandiego.
>

     Interesting approach! Like, if it works, it works.

     The usual way to capture an entire program is to have a ROM with
modified code. So, for example, a RESET followed quickly by an M will
automatically move $000-$7FF to the hires-1 display area and then place
you in the monitor. Since the hires display is usually used for display,
you do no lose any of the program code.


....
> > A vendor will often employ the same
> > or a very similar protection for several products.
> 
> Or a company has a copier for it, e.g. Print Shop and Dazzle Draw, or
> MECC's licensed copier (which by the way wouldn't copy itself, by
> default ;)
>

     The best single MECC copier is a non-company ware named "MECC
Copy".

 
> Hubbard Star Gazer would be considered an educational title.  Are there
> any other titles even listed by Hubbard during the 1980's? ....

     Not that I know of. Sometimes, old wares will copy surprisingly
well using FID or COPYA with a DOS modified to remove error checking.
Another useful trick, especially with odd track length protection, is to
use Copy II+ bit copy with Preserve Track Length set and turn down the
speed (e.g. to a reading of 205 or so on Copy II+'s Verify Speed) on the
drive in which the original is located.

 

Rubywand